Prime Minister Ehud Olmert was interrogated for a fifth time at his Jerusalem residence on Friday by National Fraud Unit detectives. The session lasted for three hours after Olmert offered detectives an extra half an hour to ask him about the Rishon Tours double-billing and Talansky cash-envelopes investigations. National Fraud Unit detectives later briefed Israel Police head investigator Cmdr. Yochanan Danino on the session. Police are expected to decide this week whether a sixth interrogation of the prime minister is needed. Meanwhile, police continue to provide no explanation for the arrest and subsequent house arrest of former Olmert aide Eldad Rotman on Thursday night. Rotman worked for Olmert while the premier served as minister of trade, industry and labor between 2003 and 2005. The prime minister is under investigation for allegedly appointing cronies to the ministry's Small and Medium and Enterprises Authority and to other government bodies during that time, although it is not clear whether Rotman's arrest is linked to that particular investigation. A former senior National Fraud Unit detective, Dep.-Cmdr. (ret.) Boaz Guttman, said the arrest was aimed at keeping Rotman from disrupting the investigation by communicating with others.